Biodegradable Segment of a Smoking Article

ABSTRACT

A segment of a smoking article is shown, comprising a fiber-based web material and a wrapping material, which wraps the fiber-based web material, wherein the fiber-based web material comprises at least 40% pulp fibers and less than 10% non-natural polymers, respectively with respect to the mass of the web material, has a basis weight of at least 10 g/m 2  and at most 70 g/m 2 , and has a thickness of at least 25 m and at most 400 μm, wherein said web material in the segment has an area of at least 20 cm 2  and at most 90 cm 2  per cm 3  volume of the segment, wherein the segment without the wrapping material has a density of at least 50 kg/m 3  and at most 300 kg/m 3 , and wherein a parameter Z, which is defined by Z=ρ Web +5·ρ seg +12·A Web , satisfies the inequality 1300≤Z≤2800, wherein ρ Web  is the density of the web material in kg/m 3 , ρ Seg  is the density of the segment without wrapping material in kg/m 3 , and A Web  is the area of the web material per volume of the segment in cm 2 /cm 3 .

FIELD OF INVENTION

The invention relates to a segment of a smoking article, in particular to a segment for cooling or filtration of the aerosol flowing in the smoking article, which biodegrades better than segments known in the prior art and which provides a good combination of properties in relation to draw resistance and filtration efficiency.

BACKGROUND AND PRIOR ART

Smoking articles are typically rod-shaped articles, which consist of at least two rod-shaped segments arranged next to each other. One segment contains a material that is capable of forming an aerosol upon heating and at least one further segment serves to influence the properties of the aerosol.

The smoking article can be a filter cigarette in which a first segment contains the aerosol-forming material, in particular tobacco, and a further segment is formed as a filter and serves the filtration of the aerosol. In this regard, the aerosol is produced by burning the aerosol-forming material and the filter primarily serves to filter the aerosol and to provide a defined draw resistance to the filter cigarette.

However, the smoking article can also be a so-called heated tobacco product, in which the aerosol-forming material is only heated but not burnt. In this regard, the number and amount of harmful substances in the aerosol is reduced. Such a smoking article also consists of at least two, more often, however, of more, in particular of four segments. One segment contains the aerosol-forming material, which typically comprises tobacco, reconstituted tobacco or tobacco prepared by other processes. Further segments in the smoking article which are optional to a certain extent serve to transfer the aerosol, to cool the aerosol or to filter the aerosol.

The segments are usually wrapped by a wrapping material. Very often, paper is used as a wrapping material.

In the following, unless explicitly stated or directly derivable from the context, “segment” should be understood to mean the segment of a smoking article that does not contain the aerosol-forming material, but, for example, serves to transfer, cool or filter the aerosol. From the prior art it is known to produce such segments from non-natural polymers such as cellulose acetate or polylactic acids. After consumption of the smoking article, the smoking article has to be disposed of properly. In many cases, however, the consumer simply drops the consumed smoking article in the environment, and attempts to restrict this behavior by information or fines had little success.

As cellulose acetate and polylactic acids are degraded in the environment only very slowly, there is an interest in the industry to produce the segments of the smoking article from other materials that biodegrade better. Furthermore, for example, the European Union plans regulations that substantially reduce or prohibit the use of non-natural polymers in smoking articles, so that for this reason too, there is an interest in having alternative segments for smoking articles available.

A segment in a smoking article has to fulfill various requirements. A first requirement is to filter the aerosol. Often, this filtration is selective, which means that certain substances are removed from the aerosol and thus it influences the taste of the aerosol. With respect to filtration, one would like to have segments that have a particularly high filtration efficiency, for example if they primarily serve filtration, as well as such that have a low filtration efficiency, for example if they are primarily intended to transfer or cool the aerosol.

A further requirement is to provide a certain draw resistance. During smoking, the consumer expects a certain resistance, i.e. a certain pressure difference, in order to draw aerosol from the smoking article. The segments for smoking articles are thus often designed such that they have a certain draw resistance.

A further requirement is to cool the aerosol. Immediately after its formation, the aerosol has a temperature of several 100° C. and has to be cooled to a temperature acceptable for the consumer while it is flowing through the smoking article. According to the prior art, this is typically achieved by conducting heat from the aerosol.

Finally, a further requirement is to provide sufficient mechanical stability to the smoking article. The consumer should not be able to compress the smoking article accidentally during normal consumption of the smoking article; thus, the segments need to have a certain hardness. This is also achieved in part by the selection of a suitable wrapping material.

Attempts to combine all these requirements with good biodegradability have so far not been sufficiently successful.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a segment for a smoking article, which can biodegrade better than conventional segments in smoking articles and which is in any case not worse than conventional segments with respect to filtration properties, cooling effect and draw resistance.

This object is achieved by a segment according to claim 1 and a smoking article according to claim 21. Advantageous further embodiments are disclosed in the dependent claims.

The inventors have found that certain fiber-based web materials for segments in smoking articles are suitable to fulfill at least the requirement with respect to the biodegradability. Fiber-based web materials describes all web-shaped materials from staple fibers that can be formed into segments for smoking articles. Suitable fiber-based web materials are in particular paper or nonwovens. In the following, without exception, “web material” is understood to mean a fiber-based web material for use in smoking articles.

The inventors have further found that a certain combination of properties of the web material and the segments manufactured therefrom allow the various additional requirements to be satisfied in a particularly advantageous manner.

Specifically, the segment according to the invention comprises a wrapping material and a web material, which is wrapped by the wrapping material. The web material comprises at least 40% pulp fibers and less than 10% non-natural polymers, wherein the percentages refer to the mass of the web material. Furthermore, the web material has a basis weight of at least 10 g/m² and at most 70 g/m², a thickness of at least 25 μm and at most 400 μm. In the segment said web material has an area of at least 20 cm² and at most 90 cm² per cm³ volume of the segment. The segment manufactured from the web material has a density of at least 50 kg/m³ and at most 300 kg/m³ without the wrapping material. Finally, for the density of the web material (ρ_(web)) in kg/m³, the density of the segment without the wrapping material (ρ_(seg)) in kg/m³ and the area of the web material per cm³ volume of the segment (A_(web)) in cm²/cm³, the following inequality has to hold

1300≤ρ_(Web)+5·ρ_(seg)+12·A _(Web)≤2800.

According to the findings of the inventors the draw resistance, the filtration efficiency and the cooling effect of the segment are determined by the structure and the amount of the web material in the segment. In this regard, a porous structure of the web material increases the heat transfer and the filtration efficiency. Apart from the structure of the web material, the amount of web material in the segment is also important. It is specified on the one hand by the area of the web material in the segment per volume of the segment, wherein a higher area per volume increases draw resistance, filtration efficiency and heat transfer, and on the other hand by the density of the segment without the wrapping material, wherein a higher density primarily increases the draw resistance. In particular for the cooling effect of the segment, apart from the area available for the heat transfer, the densities of the web material and the segment are also important, because they determine the conduction of the heat.

Now, the inventors have found that within the aforementioned limits for the basis weight of the web material, the thickness of the web material, the density of the web material, the area of the web material per volume in the segment and the density of the segment without the wrapping material, a particularly good combination of properties can be achieved if the aforementioned inequality is satisfied for the parameter calculated from the density of the web material, the density of the segment without wrapping material and the area of the web material per volume of the segment.

The web material in the segment of the smoking article comprises pulp fibers, wherein at least 40% of the mass of the web material is formed by pulp fibers. Pulp fibers consist of natural polymers and are capable of biodegrading well, whence a first advantage of the invention. A further advantage that is essential to the invention results from the fact that pulp fibers are hygroscopic. The aerosol in the smoking article contains water and the pulp fibers can absorb part of this water and thus contribute to cooling of the aerosol. In this regard, in contrast to segments from other materials, heat is no longer transferred, but a part of the water in the aerosol together with the heat energy contained in the water is retained. Thus, an aerosol reaches the consumer of the smoking article which is at a temperature that is not necessarily substantially reduced, but which contains substantially less heat energy and is thus more acceptable for the consumer.

Preferably, the content of pulp fibers in the web material is therefore higher and is preferably at least 60%, particularly preferably at least 90% and highly particularly preferably at least 99%, respectively with respect to the mass of the web material.

The pulp fibers can be wood pulp fibers from deciduous trees or coniferous trees, but also from other plants such as hemp, flax, sisal, jute, abaca or esparto grass and are manufactured according to processes known in the art. Mixtures of pulp fibers of different origins can also be used.

In order to ensure good biodegradability of the segment, the web material should contain less than 10% of its mass of non-natural polymers. Natural polymers in this regard are polymers that are sourced directly from natural raw materials without a chemical modification or a modification of the composition or that are chemically identical to such polymers sourced from nature. Specifically, pulp fibers consist of natural polymers, and also fibers from regenerated cellulose belong to the natural polymers. For cellulose acetate and polylactic acids, however, chemical modifications have taken place, so that they do not belong to natural polymers and, even though the raw materials exist in nature, these raw materials have at least been modified such that fast biodegradation is no longer ensured. Additionally, all polymers sourced from mineral oils, such as polyethylene, polypropylene, polyester or polystyrene, are non-natural polymers.

Preferably, the web material contains less than 5% of the mass of the web material of non-natural polymers, and particularly preferably less than 1% of the mass of the web material. An optimal biodegradability is achieved when the web material contains no non-natural polymers, for which reason this is a highly particularly preferred embodiment.

The web material can contain fibers from regenerated cellulose, such as viscose fibers, modal fibers, Lyocell® or Tencel®, wherein their content is preferably less than 60% of the mass of the web material and particularly preferably less than 40% of the mass of the web material. The amount of fibers from regenerated cellulose can be selected to further optimize the filtration efficiency.

The web material can contain filler materials, wherein the filler materials are preferably formed by calcium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, titanium dioxide and silicates or mixtures thereof. A particularly preferred filler material is precipitated calcium carbonate. The content of filler materials with respect to the mass of the web material is preferably at least 0%, particularly preferably at least 5% and highly particularly preferably at least 10% and preferably at most 40%, particularly preferably at most 35% and highly particularly preferably at most 30%. Because filler materials absorb substantially less water than the pulp fibers, an increase in the content of filler materials for the same basis weight of the web material can contribute to a reduction of the filtration efficiency for water. In this manner, the cooling effect of the segment can be influenced.

The web material can also be coated. In a preferred embodiment, the web material is coated with polyvinyl alcohol or a polysaccharide, whereupon the filtration efficiency for water is reduced and the aerosol is thus dried less. In a particularly preferred embodiment, the polysaccharide is selected from the group consisting of starch, carboxymethylcellulose, guar, dextrin, pectin or mixtures thereof. It should be noted that polyvinyl alcohol is not a natural polymer and the amount of non-natural polymers does not exceed 10% of the mass of the web material.

The web material can also be impregnated. In contrast to coating, in the case of impregnation, the applied composition does not only remain on the surface, but essentially penetrates into the structure of the web material. In a preferred embodiment the web material is impregnated with glycerol or propylene glycol. These substances can increase the filtration efficiency for glycerol, which often serves as a humectant in the aerosol-forming material of the smoking article and enhances the formation of the aerosol.

The web material can also contain flavors to adjust the taste of the aerosol. The flavors can be contained in the web material in chemically bound form or in physically bound form, for example, encapsulated. Preferably, the flavors are selected from the group consisting of menthol, ethyl vanillin glucoside, vanillin and ethyl vanillin.

The skilled person can select further components of the web material, such as sizing agents, for example AKD, ASA or resins, or further additives and process aids according to his experience, wherein it should be noted that the amount of non-natural polymers has to be less than 10% of the mass of the web material.

The basis weight of the web material is between 10 g/m² and 70 g/m² and preferably between 20 g/m² and 60 g/m² and particularly preferably between 25 g/m² and 50 g/m².

The basis weight can be determined in accordance with ISO 536:2012. The selection of the basis weight influences the processability of the web material, in particular the process of crimping or folding, and the amount of material for the segment. The preferred ranges combine the amount of material with the resulting segment properties particularly well.

The thickness of the web material is between 25 μm and 400 μm and preferably between 35 μm and 150 μm and particularly preferably between 40 μm and 100 μm. As with the basis weight, the thickness of the web material is of importance for the processability and in the case of the desired properties of the segment, the preferred ranges result in a thickness that is particularly well suited for crimping or folding. The thickness can be determined in accordance with ISO 534:2011.

The basis weight and the thickness together influence, via the density, the properties of the segment manufactured from the web material. The density of the web material is preferably between 100 kg/m³ and 1200 kg/m³, particularly preferably between 200 kg/m³ and 700 kg/m³ and highly particularly preferably between 300 kg/m³ and 600 kg/m³. The density describes the porous structure of the web material and thus a quantity that is essential for the filtration efficiency, the heat transfer and the draw resistance. The preferred ranges allow for a good combination of draw resistance and filtration efficiency. The density can be determined in accordance with ISO 534:2011.

The segment contains between 20 cm² and 90 cm² web material per cm³ volume of the segment, preferably between 30 cm²/cm³ and 80 cm²/cm³ and particularly preferably between 35 cm²/cm³ and 70 cm²/cm³, respectively with respect to the volume of the segment. The area of the web material per volume of the segment describes how densely the web material is packed in the segment. It thus has effects on the draw resistance, but also on the filtration properties, the heat transfer and the hardness of the segment. The area of the web material can be determined, for example, by weighing the web material and calculation from the nominal or measured basis weight of the web material.

The density of the segment itself, without the wrapping material, is between 50 kg/m³ and 300 kg/m³, preferably between 60 kg/m³ and 250 kg/m³ and particularly preferably between 70 kg/m³ and 200 kg/m³. This parameter also has essential effects on the draw resistance, the filtration efficiency and the hardness of the segment. The density of the segment is indicated without the wrapping material, because the wrapping material has little influence on the draw resistance, the filtration efficiency or the heat transfer. The determination of the density of the segment can be by calculation. In this regard, firstly, the volume of the segment is determined, which, for example, can be calculated from the diameter and the length for a cylindrical segment. The influence of the wrapping material on the diameter can be ignored. The mass of the segment can be determined by weighing, wherein the segment is wrapped with the wrapping material. The mass of the wrapping material can be determined from the area of the wrapping material and the nominal or measured basis weight of the wrapping material. As an example, for a typical cylindrical segment, the area of the wrapping material results from the circumference of the segment and the overlap of the wrapping material with itself as well as from the length of the segment.

The mass of the wrapping material is subtracted from the mass of the segment with wrapping material and its density is calculated by division by the volume of the segment. A numerical example is carried out in detail further below.

As the density of the web material, the density of the segment without wrapping material and the area of the web material in the segment per volume of the segment all have an influence on the draw resistance, the filtration efficiency and the heat transfer of the segment, and thereby interact in a complex manner, the inventors have found that only a specific combination of these properties can properly satisfy the requirements for a segment. It was found that a parameter Z calculated from these properties is relevant therefor, which is calculated by

Z=ρ _(Web)+5·ρ_(seg)+12·A _(Web),

wherein

ρ_(Web) is the density of the web material in kg/m³

ρ_(seg) is the density of the segment without wrapping material in kg/m³, and

A_(Web) is the area of the web material per volume of the segment in cm²/cm³.

This parameter Z should be at least 1300 and at most 2800, preferably at least 1350 and at most 2600 and particularly preferably at least 1400 and at most 2400. Only in this manner is a segment obtained with favorable properties and only in the preferred ranges is a particularly favorable compromise of draw resistance and filtration efficiency obtained.

The wrapping material of the segment is preferably a paper and particularly preferably a paper with a basis weight of at least 20 g/m² and at most 150 g/m² and particularly preferably a paper with a basis weight of at least 50 g/m² and at most 120 g/m². In order to obtain favorable properties for the segment, the density of the segment and thus the hardness are comparatively low. Thus, wrapping materials with a basis weight of 50 g/m² to 150 g/m² can further improve the hardness of the segment. The basis weight, however, must not be too high, because otherwise, the restoring forces of the wrapping material make the manufacture of the segment, in particular gluing of the wrapping material with itself, more difficult.

The bending stiffness of the wrapping material can be equally as important as the basis weight in order to obtain a favorable hardness of the segment. The bending stiffness should thus preferably be at least 0.05 Nmm and at most 0.90 Nmm, particularly preferably at least 0.10 Nmm and at most 0.80 Nmm. The bending stiffness can be determined in accordance with ISO 5628:2012, particularly in accordance with the two-point method described in this standard. The bending stiffness can depend on the direction, in which the sample is taken from the web material. The features defined by the aforementioned preferred and particularly preferred ranges are obtained when the bending stiffness in at least one direction lies in the defined preferred or particularly preferred ranges.

The segment according to the invention is preferably cylindrical and preferably has a diameter of at least 5 mm and at most 9 mm, particularly preferably of at least 7 mm and at most 8.5 mm.

The segment according to the invention is preferably at least 4 mm and at most 40 mm long, particularly preferably at least 6 mm and at most 35 mm and highly particularly preferably at least 10 mm and at most 28 mm.

The segment according to the invention can be a component of a smoking article, so that a smoking article according to the invention comprises an aerosol-forming material and the segment according to the invention.

In a preferred embodiment, the smoking article is a filter cigarette comprising at least a segment according to the invention and a further segment which contains tobacco. In a particularly preferred embodiment, the segment according to the invention is a segment of the filter of a filter cigarette.

In a further preferred embodiment, the smoking article is a smoking article that contains an aerosol-forming material, which during intended use of the smoking article is only heated but not burnt, and which contains at least one segment according to the invention and a filter segment, wherein the at least one segment according to the invention is arranged between the aerosol-forming material and the filter segment. In this arrangement, the at least one segment according to the invention primarily serves to cool the aerosol.

The segment according to the invention can be manufactured in accordance with processes which are known in the art. Such processes typically comprise crimping or folding the web material, the manufacture of a continuous rod from the web material, wrapping the continuous rod with a wrapping material and cutting the wrapped rod into segments of the desired size.

Smoking articles using the segment according to the invention can also be manufactured in accordance with processes in the art.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a table (Table 1), in which the compositions of 25 web materials are summarized.

FIG. 2 shows a table (Table 2), in which characteristic properties of the web materials (width, basis weight, thickness, density) of the 25 web materials of Table 1 are summarized.

FIG. 3 shows a table (Table 3), in which characteristic properties (mass, density, area, parameter Z) of 25 segments, which were manufactured from the web materials of Tables 1 and 2, are summarized.

FIG. 4 shows a table (Table 4), in which functional properties of the segments of Table 3 (draw resistance, filtration efficiency for nicotine, water and glycerol) are summarized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described more precisely by way of a few embodiments according to the invention and compared with examples not according to the invention.

Different fiber-based web materials were manufactured according to processes known in the art and reels with a width of 175 mm to 315 mm were cut. The reels of the web materials were crimped and of each a continuous rod was manufactured and wrapped with a wrapping material with a basis weight of 78 g/m². The rod with the wrapping material had a diameter of 7.85 mm, wherein the wrapping material had a width of 27 mm and thus overlapped by about 2.3 mm for gluing to itself.

The composition of the web materials is given in Table 1. All of the web materials were manufactured from wood pulp; for the two web materials No. 22 and 23 Lyocell® fibers were also used, wherein the indicated percentage of 40% is with respect to the mass of Lyocell® fibers in the total fiber mass in the web material. The web materials 4-6, 12 and 13 also contained 29.5% of their mass of precipitated calcium carbonate (CaCO₃).

Web materials 16-21, 24 and 25 were coated with an oxidized starch and the web materials 14, 15, 18 and 19 were impregnated with glycerol. The web materials 20 and 21 were impregnated with propylene glycol.

The basis weight of the web materials was determined in accordance with ISO 536:2012 and the thickness and the density were determined in accordance with ISO 534:2011. The results are given in Table 2, wherein the numbers of the web materials correspond to those of Table 1.

The rods manufactured from the web materials were cut into rods each with a length of 108 mm and their mass was determined by weighing.

The data for the rods manufactured from the web materials 1-25 are given in Table 3, wherein again, the numbers of the web materials correspond to those of Table 1. The mass in Table 3 in this regard is the mass of a 108 mm long rod with a wrapping material with a basis weight of 78 g/m². The density was calculated as follows from the mass of the rod and the known geometry.

The mass of the wrapping material, which was 27 mm wide and 108 mm long, was

78 g/m²×0.027 m×0.108 m=0.227 g.

The volume of the rod was calculated from the known geometry, thus

π/4×(7.85 mm)²×108 mm=5227 mm³.

In this regard, the thickness of the wrapping material was ignored. The mass of the wrapping material was subtracted from the mass of the rod with wrapping material and the result was divided by the volume. Thus, for example, the density of the rod manufactured from web material 1 was

(0.71g−0.227 g)/5227 mm³=92.4 kg/m³.

The parameter Z is also shown in Table 3, which is calculated from

Z=ρ _(Web)+5·ρ_(seg)+12·A _(Web),

wherein

ρ_(Web) is the density of the web material in kg/m³

ρ_(Seg) is the density of the segment without wrapping material in kg/m³, and

A_(Web) is the area of the web material per volume of the segment in cm²/cm³.

The parameter Z is independent of the geometry, in particular the diameter and the length of the rod or the segment, and characterizes only the inner structure of the segment.

The draw resistance of the 108 mm long rods was measured in accordance with ISO 6565. Segments with a length of 18 mm were cut from the rods, and smoking articles manufactured therefrom.

The smoking article was a so-called heated tobacco product, in which the tobacco contained in the smoking article is only heated. The smoking article consisted of a segment with the tobacco followed in the flow direction by a transfer segment, in which the aerosol can condense, and further followed by the segment according to the invention, which here primarily serves to cool the aerosol, and finally by a filter segment.

The smoking article was heated in a commercially available heating device and smoked in accordance with the method given in ISO 3308. The filtration efficiency for nicotine, water and glycerol was measured for the segments manufactured from the web materials 8-25. In this regard, the filtration efficiency is the difference between the amount of substance flowing into the segment and the amount of substance flowing out of the segment, with respect to the amount of substance flowing into the segment. The filtration efficiency is expressed as a percentage and was determined by this method for nicotine, water and glycerol for an 18 mm long segment.

In Table 4, the draw resistance of a 108 mm long rod and the filtration efficiency of an 18 mm long segment for nicotine, water and glycerol are shown. Here again, the numbers of the web materials correspond to those of Table 1.

The segments manufactured from the web materials 1-25 are segments according to the invention, which have a parameter Z of about 1300 to about 2250. The draw resistance of the 108 mm long rod is between 17.9 mmWG and 63.9 mmWG and enables the design of segments, which either transfer the aerosol and only have a low draw resistance or which filter the aerosol and additionally allow the draw resistance to be increased. In particular, a comparison of the web materials 2 and 11, which are identical with respect to their composition, show the influence of the density of the segment on the draw resistance. A segment from web material 2 with a density of the segment of 73.3 kg/m³ provides a draw resistance (108 mm) of 23.8 mmWG, while a segment manufactured from web material 11 with a density of 170.5 kg/m³ has a draw resistance (108 mm) of 54.5 mmWG. This shows the importance of the density of the segment, for which reason it is an essential component of the parameter Z. The draw resistance, however, is not solely determined by the density of the segment.

The web materials 6 and 7 have similar basis weights, wherein web material 6, however, contains 29.5% calcium carbonate and thus has a substantially higher density. The segments manufactured therefrom have similar densities and also the area of the web material per volume of the segment is similar. Nevertheless, they differ substantially in draw resistance, which is 63.9 mmWG for the rod (108 mm) manufactured from web material 6 and 30.5 mmWG for the rod (108 mm) manufactured from web material 7. This shows that the density of the web material itself has an independent effect on the properties of the segment manufactured therefrom and thus also constitutes an essential component of the parameter Z.

The area of the web material per volume of the segment depends on the density of the web material and the density of the segment without wrapping material, and thus is also an essential property of the draw resistance and therefore is also a component of the parameter Z.

The segments of the web materials 16-21 coated with starch all exhibit a lower filtration efficiency for water than the segments from the comparable web materials 8, 9 and 11, while they hardly differ in the filtration efficiencies for nicotine and glycerol. This therefore shows that a coating with oxidized starch can be used to adjust the filtration efficiency for water.

Impregnation of the web materials 18-21 with glycerol or propylene glycol results in a substantially higher filtration efficiency for nicotine and glycerol in the segments manufactured therefrom compared with the segments from the web materials 16 and 17, which do not have such an impregnation. Thus, the filtration efficiency for nicotine and glycerol can be adjusted by the impregnation.

In summary, all segments manufactured from the web materials 1-25 are useful as segments in a smoking article and can serve for cooling the aerosol as well as for filtration of the aerosol. The biodegradability of all segments manufactured from the web materials 1-25 resulted directly from the components used and was not tested further. It was shown that with the segments according to the invention, favorable properties for use in smoking articles can be obtained and additionally, excellent biodegradability can be achieved.

The following two examples that are not according to the invention show that the parameter Z is essential to the differentiation between segments according to the invention and segments not according to the invention.

A segment with a density without wrapping material of 90.4 kg/m³ and an area of the web material per volume of the segment of 36.9 cm²/cm³ was manufactured from web material 7.

The parameter Z for this is segment was

350.0+5·90.4+12·36.9=1244.8

and thus lies outside the range according to the invention of 1300 to 2800.

The 108 mm long rod from this web material had a draw resistance of just 12.3 mmWG, which is too low for application in smoking articles. In addition, the hardness of the segment despite the wrapping material with 78 g/m² is not sufficient for further processing into a smoking article. It should be noted that this segment satisfied all of the requirements according to the invention, with the exception of those related to parameter Z.

A segment with a density without the wrapping material of 233.9 kg/m² and an area of the web material per volume of the segment of 89.9 cm²/cm³ was manufactured from web material 12. The parameter Z for this segment was

604.7+5 233.9+12 0.89.9=2853.6

and thus lies outside the range according to the invention of 1300 to 2800.

The filtration efficiency of this segment for water was more than 65% despite the high content of calcium carbonate in web material 12, and therefore produced too dry an aerosol and thus resulted in a taste which was not acceptable to the consumer. It should be noted that again, this segment satisfied all of the requirements according to the invention, with the exception of those related to parameter Z.

The two comparative examples not according to the invention thus show that the parameter Z is essential for obtaining a segment with satisfactory properties. 

1. Smoking article, comprising an aerosol-forming material which during smoking is heated, but not burnt, and segment, said segment comprising a fiber-based web material and a wrapping material, which wraps the fiber-based web material, wherein the fiber-based web material comprises at least 40% pulp fibers and less than 10% non-natural polymers, respectively with respect to the mass of the web material, has a basis weight of at least 10 g/m² and at most 70 g/m², and has a thickness of at least 25 μm and at most 400 μm, wherein said web material in the segment has an area of at least 20 cm² and at most 90 cm² per cm³ volume of the segment, wherein the segment without the wrapping material has a density of at least 50 kg/m³ and at most 300 kg/m³, and wherein a parameter Z, which is defined by Z=ρ_(Web)+5·ρ_(seg)+12·A_(Web), satisfies the inequality 1300≤Z≤2800, wherein ρ_(Web) is the density of the web material in kg/m³, ρ_(Seg) is the density of the segment without wrapping material in kg/m³, and A_(web) is the area of the web material per volume of the segment in cm²/cm³, wherein the wrapping material is formed by paper with a basis weight of at least 20 g/m² and at most 150 g/m², and wherein the wrapping material has a bending stiffness of at least 0.05 Nmm and at most 0.00 Nmm.
 2. Smoking article according to claim 1, wherein the content of pulp fibers in the web material is at least 60% with respect to the mass of the web material.
 3. Smoking article according to claim 1, wherein the pulp fibers are formed by wood pulp fibers which are sourced from deciduous trees or coniferous trees, from hemp, flax, sisal, jute, abaca or esparto grass, or mixtures thereof.
 4. Smoking article according to claim 1, wherein the web material contains less than 5% of its mass of non-natural polymers.
 5. Smoking article according to claim 1, wherein the web material contains fibers from regenerated cellulose, wherein their content is less than 6% of the mass of the web material.
 6. Smoking article according to claim 1, wherein the web material contains filler materials, wherein the filler materials are formed by calcium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, titanium dioxide, silicates or mixtures thereof.
 7. Smoking article according to claim 1, wherein the content of filler materials with respect to the mass of the web material is at least 5% and at most 35%.
 8. Smoking article according to claim 1, wherein the web material is coated with polyvinyl alcohol or a polysaccharide.
 9. Smoking article according to claim 1, wherein the web material is impregnated with glycerol or propylene glycol.
 10. Smoking article according to claim 1, wherein the web material contains flavors, wherein the flavors are contained in the web material in a chemically bound form or in a physically bound form.
 11. Smoking article according to claim 1, wherein the basis weight of the web material is between 20 g/m² and 60 g/m².
 12. Smoking article according to claim 1, wherein the thickness of the web material is between 35 μm and 150 μm.
 13. Smoking article according to claim 1, wherein the density of the web material is between 200 kg/m² and 700 kg/m³.
 14. Smoking article according to claim 1, which contains between 35 cm²/cm³ and 70 cm²/cm³ of web material per cm³ volume of the segment.
 15. Smoking article according to claim 1, with a density, without the wrapping material, which between 70 kg/m³ and 200 kg/m³.
 16. Smoking article according to claim 1, wherein the parameter Z is at least 1350 and at most
 2600. 17. Smoking article according to claim 1, wherein the wrapping material is formed by paper with a basis weight of at least 50 g/m² and at most 120 g/m².
 18. Smoking article according to claim 1, wherein the wrapping material has a bending stiffness of at least 0.10 mm and at most 0.80 Nmm.
 19. Smoking article according to claim 1, wherein the segment is cylindrical and has a diameter of at least 5 mm and at most 9 mm.
 20. Smoking article according to claim 1, wherein the segment is at least 4 mm and at most 40 mm long.
 21. (canceled)
 22. (canceled)
 23. Smoking article according to claim 1, wherein the segment is arranged between the aerosol-forming material and a filter segment.
 24. Smoking article according to claim 1, wherein the content of pulp fibers in the web material is at least 90% with respect to the mass of the web material.
 25. Smoking article according to claim 8, wherein the polysaccharide is selected from the group consisting of starch, carboxymethylcellulose, guar, dextrin, pectin or mixtures thereof.
 26. Smoking article according to claim 10, wherein the flavors are selected from the group consisting of menthol, ethyl vanillin glucoside, vanillin and ethyl vanillin.
 27. Smoking article according to claim 1, wherein the parameter Z is at least 1400 and at most
 2400. 